He’s kind of a special case, definitely far from the norm (speaking as someone who’s been in Japanese learning circles for decades). Only had 2 years of formal language education, still admitted he had a bunch of help on his term papers. 5 years in kanji terms would be more than one new one a day, every day for 5 years. Genki 1&2 in 2 years, I guess 5 years is feasible for grammar - with the understanding that the intermediate book I mentioned is as long as Genki 1&2 combined, and the Japanese book I mentioned is twice as long as that. 900hours of study in 5 years is not unrealistic if you put in an hour every weekday.

5 years is about right if you're doing it full time AND working your ass off. That's what my wife did. IUC is an amazing but hard program.

Also about Kanji memorization - its not really necessary to learn every Kanji - that's crazy - there are like 50,000. There's the standard Joyo which is 2000+ or so, and then depending on one's area of expertise, characters peculiar to that field. Also, its not like memorizing each character from scratch - we learn the basic radicals and then learn to combine them.

Just a kind of very simple example of the thought process that goes into memorizing kanji -

語 hanashi or story. Also read as "go". I know that it starts with the radical for "word" 言 and then add a five 五 (which incidentally cues the pronunciation "go") on top of a mouth 口. Previously, I would have learned each of these elements. Combining them is just another step.

Also, there's no shame in using Kanji dictionaries. Even Japanese people often have difficulty reading kanji and since the advent of autopredict typing, people don't know how to write kanji anymore by hand.

Those who, even with distracted minds,
Entered a stupa compound
And chanted but once, “Namo Buddhaya!”
Have certainly attained the path of the buddhas.
-Lotus Sutra, Expedient Means Chapter

There are beings with little dust in their eyes who are falling away because they do not hear the Dhamma. There will be those who will understand the Dhamma.
-Ayacana Sutta